1. Field of the Invention
The present invention relates to an automatic tension device of a brake, and more particularly to an automatic tension device of a brake of a bicycle, wherein the automatic tension device may be used to adjust and shorten the braking gap between the brake pad and the tire automatically.
2. Description of the Related Art
A conventional tension device of a brake in accordance with the prior art is shown in FIG. 1. The handlebar 1A is provided with a fixing base 2, and a brake lever 3 is pivotally mounted on the fixing base , 2. A cable guide seat 4 is mounted on the brake lever 3. The cable 5 has a first end secured to the cable guide seat 4 and a second end connected to a brake pad (not shown). A cable protection sheath 6 is mounted around the cable 6. A gap adjusting screw 7 is mounted on the fixing seat 2. The brake lever 3 may be pressed to draw the cable 5, thereby braking the bicycle. When the brake pad is worn to reduce its thickness, the gap adjusting screw 7 may be rotated to squeeze the cable protection sheath 6, thereby increasing the distance of the bushing of the cable protection sheath 6, so that the cable 5 may be lifted, thereby shortening the braking gap between the brake pad and the tire (not shown), so as to adjust the braking gap. However, the conventional tension device of a brake in accordance with the prior art is operated manually, thereby causing inconvenience to the user.
The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional tension device of a brake.
The primary objective of the present invention is to provide an automatic tension device of a brake, wherein the automatic tension device may be used to adjust and shorten the braking gap between the brake pad and the tire automatically.
In accordance with the present invention, there is provided an automatic tension device of a brake, comprising a fixing base, a brake lever, a worm, a worm wheel, a gap adjusting screw, a pull hook, a cable guide seat, and a cable, wherein:
the brake lever is pivotally mounted on the fixing base;
the worm is received in the fixing base, and has one end having a periphery provided with multiple one-direction ratchet teeth;
the worm wheel is received in the fixing base and meshes with the worm, the worm wheel has an inner wall formed with an inner thread;
the gap adjusting screw is received in the fixing base, the gap adjusting screw has an inner wall formed with a through hole for passage of the cable and has an outer wall formed with an outer thread screwed into the inner thread of the worm wheel;
the pull hook is pivotally mounted on the brake lever, and is provided with an one-direction ratchet tooth that may be locked with one of the multiple one-direction ratchet teeth of the worm;
the cable guide seat is mounted on the brake lever; and
the cable is extended through the through hole of the gap adjusting screw and is secured on the cable guide seat.